Automatic non-reversing stop.



No. 875,336. PATENTED DEC. 31, 1907.

' S. F. EVANS.

AUTOMATIC NON-REVERSING STOP.

APPLICATION FILED SEPT.21.1906. 2 SHEETS SHEET L PATENTED DEC. 31, 1907.

s. P. EVANS. AUTOMATIC NON -REVERSING STOP.

2 SHEETS-SHEET 2.

APPLICATION FILED 811F121. 1906..

' stop device applied thereto.

' non-reversing stop or UNITED sTAr s PATEN soo'r'r r. Evan's, 0F MmNiiAroms, MINNESOTA.

AUTOMATIb NON-REVEBSING STOP.

No. 875,336. I

Specification of Letters Patent. Application filed September 21.1905. smart. 385.600.

Patented Dec. 31, 1907.,

The object of my invention is to provide a brake device which,

while permitting free movement of a shaft in one direction will automatically resist or oppose such movement in the opposite direction;

A further and particular object is to provide a friction stop ap licable to the shaft of a motor or a counter sliaft for driving an ele-' vator leg for the purpose 'of preventing backing up and the consequent choking of the leg when the power is off unexpectedly.

A still further objectis to provide a nonreversing automatic stop device of simple but strong and durable construction and one which will be positive and reliable in its action.

The invention consists generally in various constructions and combinations all as hereinafter described and particularly pointed out in the claims.

In the accompanying part of this spec fication, view of a shaft showing my improved friction Fig. 2 is a secthe fixed ring which indrawings, forming Figure 1 is an end tional view through closes the shaft and the braking shoe. F1 3 is an end view of a shaft showing a modifi: cation in the construction of the braking device Fig. 4is a sectional view illustrating the braking surface of the ring shown in Fig. 3.

i In the drawin 2 represents a shaft and 3 a portion of the ame of a motor whereon a ring 4 is secured by a suitable means as bolts 5 concentric with the shaft 2.

6 is a block keyed on the shaft and 7 are arms having weighted ends Sand pivoted at 9 intermediate to their ends to the blockfi upon opposite sides of the said shaft. Springs 10 connect the weighted ends of the arm -7 with the block 6 and normally tend to draw said ends inward and throw the opposite ends of the arm out toward the innersurface of the ring 4. When the shaft is revolved at a predetermined speed the weighted ends of the arms will be thrown outward-by centrifugal force and the opposite ends swung inwardly as usual in devices of this kind. The

opposite end of each arm 7 from the weighted end 8 is provided with a seat 11 adapted to receive a shoe 12 which has a fiat under surface tofit the bottom of the seat and a curved to outer surface 13 to engage the braking surfaceof the ring. The s oes are thicker at one end than at the other and when the shoes are swung to an operative position by the movement of their supporting arms the thicker ends of the shoes will contact first with the braking surface of the ring, then as the weighted ends of the arms 7 swing in- Wardly through the tension of their springs,

the shoes will gradually seat themselves until their surfaces 13 are in full contact with the braking surface of the ring. The shape of the shoes will cause them to have a wedging effect or strain arising from the pressure on the braking surface pivots of the arms, and the shoes Willimmediately cramp or bind and positively lock the shaft against backward movement but will slide freely over the braking surface of the ring when the Each shoe is preferably mounted on a bolt 14 centrally arranged in the seat and adjusting bolts 15 at each end of the seat permit the oscillation of the shoe and the adjustment of its curved surface with respect to the braking surface of the ring. By means of this adjustment, the proper angle of engagement of each shoe with its braking surface can be determined to insure positive clamping of the shaft and the absolute prevention of backward movement. Normally the springs 10 will swing the weighted. ends of the arms inward and press the friction shoe againstthe braking surface of the ring and backward movement of positively prevented. As soon, however, as the motor shaft is revolved in the opposite or forward direction at a sufiicient speed to overcome the power of the springs 10, the

shoes will be automatically withdrawn from contact with the braking surface and the shaft will be allowed to revolve freely.

In Fig. 3 I have shown a modification which consists in providing the braking surface of the rin with a serles of ends of the arms 7 1n place of the friction shoes and pressed by means of springs 18 into engagement with ring when the'shaft 1S revolved in one direction being sustained by the 75 shaft is revolved forward. 80

the shaft and motor will be 95 V shouldersor teeth 16 exten ng transversely thereof at intervals and engaged by dogs 17 carried on the the braking surface of. the These dogs will slip over the teeth 16" and when the working speed is reached will swing .out of contact entirely with the ring surface as indicated by dotted lines in Fig. 3. Any backward movement of the shaft, however, will be positively prevented by the engagement of the dogs with the teeth 16.

I have shown this automatic non-reversing stop device as applied to the shaft of a motor. and designed particularly for 'usem connection with an elevator leg, but I do not wish to be confined to this use alone, as the invention is applicable wherever it is desired to prevent backward. or reverse movement of a shaft by means of an automatic device released by centrifugal force when the shaft is revolved in one direction, and becoming instantly op erative through its angle of engagement with the braking surface to lock the shaft against backward movement.

I claim as my inventions- 1. The combination, with a ring having an interior braking surface, of a shaft, arms pivotally supported thereby andhaving spring retracted ends adapted to be thrown out ward by centrifugal force, and means carried by the opposite ends 'of'said arms and arranged to engage the braking surface of said ring the strain arisingfrom the pressure of said means on said surface being sustained by the pivots of said arms to lock said shaft against backward movement and saidmeans swinging freely with said arms away from saidbraking surface against the tension of said springs to release said'shaft when it is revolved in'the other direction, substantially as described. j

2. The combination, with a ring having an interior braking surface, of a shaft, arms pivotally supported thereby, shoes carried by said arms and having curved surfaces adapted to contact with said'braking surface, said shoes being of greater depth at one end than at the other, the thicker ends of said shoes adapted to contact first with the braking surface of said ring, and said shoes when seated on said braking surface, having a wedging or cramping effect w lock said shaft against backward movement but-persite direction, and means for tilting said s 1 .onsaid arm whereby the angle of their bearmitting' it to be freely 'revolved in the oppooes ' ing surfaces may be changed with respect to said braking surface.

be obtained between said pivots and said. surface to lock said shaft against backward movement. I 4. The combinatiomwith a ring having an interiorbraking surface, of a shaft, arms pivotally supported at points intermediate to their ends thereon, springs connected to one end of said arms, shoes mounted in seats provided at the opposite ends of said arms and tapered from one end toward theother and having curved surfaces to engage the braking surface of saidring and adjusting bolts mounted in said seats and engaging said shoes whereby their angle with respect to stantially as described. I y

5. The combination, with a ring having an interior braking surface, of a shaft, arms pivotally supported thereon, shoes carried by said arms and having curved surfaces ad apt ed to contact with said-braking surface said said braking .urface may. be changed, sub-' shoes tapering from one end toward the" other, springs normally tending to hold said shoes in contact with said braking surface,

the angle of engagement of said shoes with o said braking surface causing the thicker ends of'said shoes to first contact with said surface,

and saidshoes becoming fully seated on said braking surface when said arms have been moved to a predetermined position through the tension of said springs, and said'shoes allowing. said shaft to revolve freely in one direction but looking it against. backward movement.

In witness whereof, I have hereunto set my hand this 15th day of September, 1906.

. SCOTT F. EVANS.

Witnesses: RICHARD PAU 'J. B. ERA. 

